The applicant has proposed a continuous-flow auxiliary artificial heart constituted by a centrifugal pump, the auxiliary artificial heart being disclosed in Japanese Published Unexamined Patent Application No. 2007-44302. In the case where such an auxiliary artificial heart is connected, a cardiac function of a person having the connected auxiliary artificial heart sometimes recovers, and cardiac function variation, more particularly, contractile variation of a left ventricle, sometimes need to be evaluated.
On the other hand, as one of the methods for evaluating the cardiac function variation, more particularly, the contractile variation of the left ventricle, there is a method for inserting a conductance catheter into the left ventricle, calculating an internal area of a closed-loop from a relationship between left ventricle internal pressure and left ventricle internal volume, the relationship being indicated in FIG. 1, and then evaluating the cardiac function variation, the method being disclosed in Japanese Published Unexamined Patent Application No. 2002-143109. The closed-loop area (stroke volume) in FIG. 1 corresponds to workload.
However, in the conventional method, it is necessary to use an expensive ultrasonic echo apparatus or to insert the conductance catheter into the left ventricle of the person having the connected auxiliary artificial heart. Therefore, the method is invasive, and not only imposes a burden on the person, but also has a possibility of causing infection or a thrombus in the case of long-time use.